Harvesting Systems
and Equipment in
British Columbia
Ministry of Forests
Forest Practices Branch
Harvesting Systems
and Equipment in
British Columbia
A.J. MacDonald
Forest Engineering Research Institute
of Canada
FERIC
Handbook No. HB-12
1999
Ministry of Forests
Forest Practices Branch
Canadian Cataloguing in Publication Data
MacDonald, A. J.
Harvesting systems and equipment in British Columbia
(FERIC handbook, ISSN 0701-8355 ; no. HB-12)
Co-published by Forest Engineering Research Institute of Canada.
Includes bibliographical references: p.
Includes index.
ISBN 0-7726-3827-6
1. Logging – British Columbia. 2. Logging – British Columbia –
Machinery. 3. Forest machinery – British Columbia. I. British Columbia. Forest Practices Branch. II. Forest Engineering Research Institute of
Canada. III. Title. IV. Series.
SD388.M32 1999
634.9’8
C99-960106-7
Prepared by
Jack MacDonald
Forest Engineering Research Institute of Canada
2601 East Mall
Vancouver, BC V6T 1Z4
for
B.C. Ministry of Forests
Forest Practices Branch
1450 Government St.
Victoria, BC V8W 3E7
http://www/for.gov.ca/hfp/hfp.htm
Published by
B.C. Ministry of Forests
Forestry Division Services Branch
Production Resources
595 Pandora Avenue
Victoria, BC V8W 3E7
Copies of this report may be obtained, depending on supply, from:
Crown Publications
521 Fort Street
Victoria, BC V8W 1E7
(250) 386-4636
http://www/crownpub.bc.ca
For more information on Forestry Division publications, visit our web site at
http://www/for.gov.bc.ca/hfd/pubs/index.htm
©
1999 Province of British Columbia
When using information from this or any Ministry of Forests report,
please cite fully and correctly.
Abstract
This handbook describes the various types of equipment and systems used for harvesting timber in British Columbia. Falling, primary transport (ground, cable, and aerial),
processing, and loading phases are described in terms of common and distinguishing
features and their relationship to operational and environmental considerations. The
handbook also discusses the effects of operating techniques, site characteristics, and
external requirements from the same operational and environmental perspectives.
Primary operating conditions for the various machine types are outlined in summary
tables. A series of flowcharts based on a risk-analysis system is used to rank the probability of conducting successful operations with different equipment on various sites.
Author
Jack MacDonald is a Senior Researcher in the Harvesting Operations group of FERIC’s
Western Division. In 1976, he graduated from the University of British Columbia with
a Bachelor of Science in Forestry — Harvesting Option, and is a Registered Professional
Forester in British Columbia.
After graduation, Jack worked for 10 years as a logging engineer in coastal British
Columbia. Since joining FERIC in 1986, Jack has worked on machine and systems evaluations, and has published several reports on ground-based and cable-based harvesting
systems. His other work at FERIC has included development of a computer program for
GIS-based harvest and silviculture planning.
Acknowledgements
The author would like to thank all those who contributed to the handbook.
The extensive knowledge of Bela Hirczy was invaluable during the interviews. Bela’s
understanding of harvesting systems in general and cable logging systems in particular
was most appreciated, and his review comments added much to the project.
Each of the woodlands managers, logging superintendents, and operating personnel who
contributed during the interviews is acknowledged and thanked. Without their input,
this project would not have been possible.
The project was directed by a steering committee comprised of industry and agency
personnel who provided guidance during the formative stages of the project, and
reviewed the drafts as they were produced. Thank you all for your input. One member
of the steering committee in particular provided valuable liaison with the Ministry of
Forests: the contribution of Larry Sluggett to the project is expressly acknowledged.
Tony Sauder and Ingrid Hedin reviewed early versions of the handbook, and provided
valuable guidance for its conclusion. Shelley Corradini created the artwork, for which
the author is grateful. FERIC researchers who participated in the review workshop are
acknowledged and thanked for their contributions.
Disclaimer
This handbook is published solely to disseminate information to FERIC members. It is not
intended as an endorsement or approval by FERIC of any product or service to the exclusion of others that may be suitable.
iii
CONTENTS SUMMARY
Abstract .................................................................................................................... iii
Author ...................................................................................................................... iii
Acknowledgements .................................................................................................. iii
Disclaimer ............................................................................................................... iii
PART 1: EQUIPMENT SELECTION ........................................................................... 1
Introduction ............................................................................................................3
About This Handbook ........................................................................................... 3
Background to Equipment Selection ..................................................................... 5
Equipment Descriptions .......................................................................................... 9
What Equipment To Consider? ..............................................................................9
Equipment Characteristics Summarized by Phase ................................................ 11
Risk-level Assessment .......................................................................................... 11
Key Factors for Primary Transport Equipment ...................................................... 19
Key Factors for Falling Equipment ........................................................................ 34
Key Factors for Processing Equipment .................................................................37
Key Factors for Loading Equipment ..................................................................... 39
Examples ................................................................................................................ 42
Example 1: Change Harvest Season .................................................................... 42
Example 2: Review Development Plan ................................................................43
Example 3: Encounter New Operating Conditions ...............................................45
PART 2: REFERENCE .............................................................................................. 47
Primary Transport Equipment ................................................................................ 49
Common Features of Ground-based Equipment .................................................. 50
Distinguishing Features of Ground-based Equipment .......................................... 53
Common Features of Cable Equipment ............................................................... 70
Distinguishing Features of Cable Equipment ........................................................ 74
Common Features of Aerial Systems .................................................................... 86
Distinguishing Features of Aerial Systems ............................................................ 88
Falling Equipment .................................................................................................. 90
Hand-falling ........................................................................................................ 90
Mechanical Falling .............................................................................................. 94
Common Features of Mechanized Falling Equipment .......................................... 95
Distinguishing Features of Mechanized Falling Equipment ................................... 98
Processing Equipment .......................................................................................... 108
Hand-bucking ................................................................................................... 108
Mechanical Processing ...................................................................................... 111
Common Features of Mechanized Processing Equipment ..................................111
Distinguishing Features of Mechanized Processing Equipment ..........................113
iv
Loading Equipment .............................................................................................. 122
Common Features of Loading Equipment ..........................................................122
Distinguishing Features of Loading Equipment ................................................... 123
Operating Techniques .......................................................................................... 127
Ground-based Primary Transport ...................................................................... 127
Cable Primary Transport ....................................................................................135
Aerial Primary Transport ....................................................................................142
Falling ............................................................................................................... 143
Processing ......................................................................................................... 145
Loading .............................................................................................................146
Combined Systems ............................................................................................147
Site and Stand Characteristics ............................................................................. 151
Terrain ..............................................................................................................151
Soil ...................................................................................................................157
Timber Characteristics ....................................................................................... 162
Weather and Climate ........................................................................................167
External Requirements ......................................................................................... 169
Forest Management Considerations ................................................................... 169
Corporate Policies and Business Practices ......................................................... 174
Layout and Development .................................................................................. 180
Selected Bibliography and Suggested Reading List ............................................... 184
Interview Sites ..................................................................................................... 187
Index ...................................................................................................................194
v
CONTENTS
PART 1: EQUIPMENT SELECTION ........................................................................... 1
Introduction ............................................................................................................3
About This Handbook ........................................................................................... 3
Background ...................................................................................................... 3
Organization .................................................................................................... 4
Intended audience ............................................................................................ 4
Background to Equipment Selection ..................................................................... 5
Context for equipment selection ....................................................................... 5
Planning horizon for equipment selection ........................................................ 7
What constitutes successful harvesting operations? ........................................... 8
Equipment Descriptions .......................................................................................... 9
What Equipment To Consider? ..............................................................................9
Equipment Characteristics Summarized by Phase ................................................ 11
Risk-level Assessment .......................................................................................... 11
Risk levels ....................................................................................................... 11
Key factors ...................................................................................................... 17
Key Factors for Primary Transport Equipment ...................................................... 19
Chart 1. Wheeled skidders .............................................................................. 19
Chart 2. Crawler skidders ................................................................................ 20
Chart 3. Flex-track skidders ............................................................................. 21
Chart 4. Clambunk skidders ............................................................................ 22
Chart 5. Forwarders ........................................................................................ 23
Chart 6. Loader-forwarders ............................................................................. 24
Chart 7. Cherry pickers and super snorkels ..................................................... 25
Chart 8. Horses ............................................................................................... 25
Chart 9. Small-scale equipment ...................................................................... 26
Chart 10. Highlead yarders ............................................................................. 27
Chart 11. Swing yarders – grapple ................................................................... 28
Chart 12. Swing yarders – slackpulling carriage and chokers .......................... 29
Chart 13. Multi-span skylines .......................................................................... 30
Chart 14. Small, single-span skylines .............................................................. 31
Chart 15. Large, single-span skylines .............................................................. 32
Chart 16. Helicopters ...................................................................................... 33
Key Factors for Falling Equipment ........................................................................ 34
Chart 17. Hand-fallers .................................................................................... 34
Chart 18. Feller-bunchers and feller-directors. ................................................. 35
Chart 19. Feller-processors .............................................................................. 36
Key Factors for Processing Equipment .................................................................37
Chart 20. Hand-buckers .................................................................................. 37
Chart 21. Dangle-head processors .................................................................. 38
Chart 22. Stroke delimbers .............................................................................. 38
Key Factors for Loading Equipment ..................................................................... 39
Chart 23. Front-end loaders ............................................................................ 39
Chart 24. Hydraulic loaders ............................................................................ 40
Chart 25. Butt ’n top loaders ........................................................................... 40
Chart 26. Line loaders ..................................................................................... 41
vi
Examples ................................................................................................................42
Example 1: Change Harvest Season ....................................................................42
Example 2: Review Development Plan ................................................................43
Example 3: Encounter New Operating Conditions ...............................................45
PART 2: REFERENCE ..............................................................................................47
Primary Transport Equipment ................................................................................ 49
Common Features of Ground-based Equipment ..................................................50
Machines travel across the ground to the cutting site ...................................... 50
Soil requires adequate load-bearing strength .................................................. 51
Suitable ground slope required ....................................................................... 51
Roads required within skidding distance ......................................................... 52
Favourable travel surface required ................................................................... 53
Downhill skidding preferred ........................................................................... 53
Distinguishing Features of Ground-based Equipment ..........................................53
Log transport method ...................................................................................... 54
Tractive system ............................................................................................... 63
Method used by skidders to hold logs ............................................................. 66
Size ................................................................................................................68
Common Features of Cable Equipment ...............................................................70
Cable should hang free and clear of the ground ..............................................70
Traffic over the ground is reduced ................................................................... 71
The yarder and cable are anchored when operating ........................................72
Roads required within yarding distance ..........................................................73
Uphill or downhill yarding is feasible ............................................................. 73
Moving cables pose a safety hazard ................................................................74
Distinguishing Features of Cable Equipment ........................................................74
Highlead and skyline configurations ............................................................... 74
Yarder mobility ............................................................................................... 77
Method used to hold logs ............................................................................... 81
Size ................................................................................................................82
Number of drums on the yarder ......................................................................84
Interlocked winch ........................................................................................... 84
Slackpulling carriage ....................................................................................... 85
Common Features of Aerial Systems ....................................................................86
Roads can be far from the cutting site ............................................................. 86
Logs are lifted clear of the ground and obstacles ............................................. 86
Equipment is expensive ..................................................................................87
Equipment capacity must closely match resource ........................................... 87
Landing is busy ............................................................................................... 87
Weather and climate affect operations ............................................................ 88
Distinguishing Features of Aerial Systems ............................................................88
Size ................................................................................................................88
Falling Equipment .................................................................................................. 90
Hand-falling ........................................................................................................ 90
Hand-falling is dangerous ............................................................................... 91
Can work on difficult terrain ........................................................................... 91
Not limited by tree size ................................................................................... 92
vii
Falling and bucking can be done concurrently ................................................ 92
Capital costs, operating costs, and productivity are low .................................. 93
Affected by weather ........................................................................................ 93
Stump height must be controlled .................................................................... 94
Can work in clearcut or partial cut .................................................................. 94
Mechanical Falling .............................................................................................. 94
Common Features of Mechanized Falling Equipment .......................................... 95
Large machine travels to each tree .................................................................. 95
Can move the tree after cutting ....................................................................... 96
Operator is enclosed in a cab ......................................................................... 96
Can work in clearcut or partial cut .................................................................. 97
Capital costs, operating costs, and productivity are high ................................. 98
Distinguishing Features of Mechanized Falling Equipment ................................... 98
Boom-mounted and drive-to-tree .................................................................... 98
Carriers for boom-mounted felling heads ...................................................... 101
Felling head .................................................................................................. 102
Levelling cab ................................................................................................ 105
Zero-clearance tail swing .............................................................................. 106
Size .............................................................................................................. 106
High-rotation head ....................................................................................... 106
Rigid attachment to boom ............................................................................. 107
Processing Equipment .......................................................................................... 108
Hand-bucking ................................................................................................... 108
Bucking can occur in various locations ......................................................... 109
Bucker can view the logs at close range ........................................................ 109
Capital costs and productivity are low .......................................................... 110
Mechanical Processing ...................................................................................... 111
Common Features of Mechanized Processing Equipment ..................................111
Faster, safer, and more capital intensive than hand-bucking .......................... 111
Processor can move logs for sorting .............................................................. 112
Mechanical aids are available for length and diameter measurements .......... 112
Distinguishing Features of Mechanized Processing Equipment ..........................113
Processor type .............................................................................................. 113
Pull-through stationary delimbers ................................................................. 116
Other processors ........................................................................................... 117
Log-measurement methods ........................................................................... 119
Feeding mechanisms ..................................................................................... 120
Size .............................................................................................................. 121
Carrier .......................................................................................................... 121
Loading Equipment .............................................................................................. 122
Common Features of Loading Equipment ..........................................................122
Distinguishing Features of Loading Equipment ................................................... 123
Machine mobility ......................................................................................... 123
Carrier .......................................................................................................... 125
Size .............................................................................................................. 126
Operating Techniques .......................................................................................... 127
Ground-based Primary Transport ...................................................................... 127
Roadside versus landing systems ................................................................... 127
Skidding pattern ............................................................................................ 130
viii
Operating period .......................................................................................... 132
Method of trail construction .......................................................................... 132
Protection of the residual stand ..................................................................... 133
Cable Primary Transport ....................................................................................135
Roadside versus landing ............................................................................... 135
Full or partial suspension .............................................................................. 137
Tailhold anchors ........................................................................................... 138
Operating period .......................................................................................... 140
Protection of the residual stand ..................................................................... 140
Aerial Primary Transport ....................................................................................142
Destination ................................................................................................... 142
Falling ............................................................................................................... 143
Tree orientation ............................................................................................ 143
Site for bucking ............................................................................................. 143
Sorting .......................................................................................................... 144
Hours of operation ........................................................................................ 144
Travel direction ............................................................................................. 144
Processing ......................................................................................................... 145
Sorting .......................................................................................................... 145
Mechanical processing in low-productivity situations ................................... 145
Loading .............................................................................................................146
Landing versus roadside ................................................................................ 146
Working on several sites simultaneously ....................................................... 146
Loading direction .......................................................................................... 146
Combined Systems ............................................................................................147
Harvesting system descriptions ..................................................................... 147
Between-phase interactions .......................................................................... 149
Site and Stand Characteristics ............................................................................. 151
Terrain ..............................................................................................................151
Slope ............................................................................................................ 151
Ground profile .............................................................................................. 152
Riparian areas ............................................................................................... 153
Gullies .......................................................................................................... 155
Roughness .................................................................................................... 157
Soil ...................................................................................................................157
Texture and moisture content ........................................................................ 157
Seasonal impact ............................................................................................ 160
Timber Characteristics ....................................................................................... 162
Tree size ....................................................................................................... 162
Volume per hectare and total cutblock volume ............................................. 164
Quality ......................................................................................................... 164
Weather and Climate ........................................................................................ 167
External Requirements ......................................................................................... 169
Forest Management Considerations ................................................................... 169
Silvicultural system ....................................................................................... 169
Utilization standards ..................................................................................... 171
Soil disturbance guidelines ........................................................................... 172
Corporate Policies and Business Practices ......................................................... 174
Operating season .......................................................................................... 174
ix
Timber flow .................................................................................................. 175
Mill specifications ......................................................................................... 175
Amount of work available ............................................................................. 176
Unique methods ........................................................................................... 177
Labour availability and training ..................................................................... 178
Equipment availability and service ................................................................ 178
Equipment transportation .............................................................................. 179
Layout and Development ..................................................................................180
Road location ............................................................................................... 180
Landing location ........................................................................................... 182
Selected Bibliography and Suggested Reading List ............................................... 184
Interview Sites ..................................................................................................... 187
Index ...................................................................................................................194
Tables
1 Relative cost ranges for primary transport
equipment under ideal conditions ...................................................................... 10
2 Characteristics of primary transport equipment ................................................... 12
3 Characteristics of falling equipment .................................................................... 13
4 Characteristics of processing equipment ............................................................. 14
5 Characteristics of loading equipment .................................................................. 15
6 Risk-level descriptions ........................................................................................ 16
7 Risk factors applicable to all harvesting equipment ............................................. 17
x
The handbook does not attempt to define a single “best” system for any site. Instead, it
presumes that readers need to be aware of the key factors that influence the probability of
achieving success with any given combination of equipment and site characteristics.
Readers will then use their own judgement to evaluate the merits of the various options.
The information in the handbook should be considered only as part of an overall process
for equipment selection which will vary from company to company.
INTRODUCTION
Many different harvesting systems and equipment are available for today’s logger.
Options range from small skidders to large skylines to helicopters, with a wide variety
in between. Two of the most important tasks faced by the logger are to select the best
harvesting system and equipment for a given site, and to use the selected equipment in
the best way possible. Each system can operate successfully under a wide range of conditions, and the conditions suitable to each system can overlap considerably. On many
sites, several systems could be used successfully, yet the conditions on other sites may
favour a single harvesting system.
Sometimes the choice between harvesting systems and equipment may result from personal or corporate preferences, especially if the options are similar. In other cases, the
same equipment can be used on different sites, but the operating techniques must be
changed to achieve the desired results. Regardless of the selection process, understanding both the economic and environmental ramifications of choosing a particular type
of equipment for use on any given site is necessary.
In addition to economic, corporate, and environmental considerations, harvestsystem selections can have legal implications. Depending on the jurisdiction, planners
may choose equipment that meets criteria or achieves results in certain site conditions
as required by various regulations.
With so many factors to consider, how does a person decide which harvesting equipment and system is best suited for a particular site? While there are as many different
ways to arrive at a decision as there are loggers, planners, and equipment owners, each
decision should be based on a thorough understanding of the implications of selecting
the different equipment types. Better understanding will lead to better decisions, and
the objective of this handbook is to help improve that understanding.
The handbook describes the various harvesting systems and equipment commonly used
in British Columbia. It describes various site characteristics, operating techniques, and
external requirements, and their effect on different types of harvesting equipment. The
information contained herein can help the logger or planner make better choices. However, the handbook is not meant to be used as a rigid guide — its role is mainly for
reference.
About This Handbook
Background
The British Columbia Ministry of Forests approached FERIC in 1995 to prepare an educational resource about harvesting systems and equipment. The new Forest Practices
Code of British Columbia Act required licensees to identify harvesting systems in logging plans, and ministry personnel to review the intended use of those systems and
equipment. However, information was lacking — no common descriptions existed of
what equipment was available for timber harvesting in British Columbia, and what the
capabilities were of that equipment. This handbook resulted from those discussions.
While this handbook grew out of a requirement of the Forest Practices Code of British
Columbia Act, FERIC’s advisory committee was apprehensive about its possible role
regarding harvest planning and the Forest Practices Code. The committee wanted to
ensure that the handbook could not be misinterpreted as providing a “cookbook” formula to determine the “correct” equipment to use for any particular harvesting site. In
About This Handbook
3
addition, it was recognized that this handbook would likely serve a wider audience than
British Columbia; such an audience may not be interested in the legal requirements for
timber harvesting in British Columbia. Lastly, it was recognized that legislation is subject to change, and that linking the handbook closely with the requirements of the
Forest Practices Code might limit its usefulness if the requirements of the Forest
Practices Code were to change.
As a result of these concerns, the handbook provides information about the capabilities of the various systems and equipment, but does not link them directly to the
requirements of the Forest Practices Code. That task is left to the reader as a separate
exercise.
Organization
The handbook is divided into two parts.
Part 1 reviews the context of equipment selection, summarizes the primary characteristics of various types of equipment, and lists the key factors to consider when
matching harvesting equipment to sites. It also includes several examples of using the
handbook to select candidate harvesting systems for specific site conditions.
Part 2 provides more detailed reference information about the various types of equipment and working conditions. It describes the harvesting phases, operating techniques,
site characteristics, and external requirements, and their effect on the suitability of the
different equipment types to various sites. The phases are primary transport, falling,
processing, and loading. Primary transport is presented first, even though it occurs
after falling, because it is commonly used to describe and classify harvesting systems.
The information in Part 1 is presented as a series of tables outlining the equipment characteristics, and charts outlining the key factors to consider for equipment selection. The
reference sections in Part 2 are organized around common characteristics and distinguishing characteristics for the various equipment types. The common characteristics are
those that define a particular type of equipment — they make a machine what it is. On
the other hand, the distinguishing characteristics separate the various makes and models of equipment from similar machines within the same type.
These characteristics, the basis of the equipment-selection process, are also the factors
that make one machine suitable for use on a particular site while rendering another
machine unsuitable.
The descriptions in Part 2 explain the effects of each factor from operational and
environmental perspectives. The operational perspectives include machine productivity, log quality, safety, and others, while the environmental items include soil
disturbance, water quality, and long-term forest productivity.
Intended audience
This handbook is intended for two different audiences. The first group consists of
people interested in timber-harvesting processes, but who may have only a rudimentary understanding of harvesting systems and equipment. Resource agency officers or
other government officials who deal with timber harvesting only incidentally may find
pertinent information in the handbook that can help with their job functions. Inexperienced foresters can also use the handbook to broaden their exposure to harvesting
systems and equipment. The second group is people such as equipment operators and
planners who are more experienced in timber harvesting in their own locale, but who
4
Introduction
want to learn about systems used in other regions of the province. The handbook may
provide them with new information that can be taken from one region and applied to
their local operations.
The handbook can be used in various ways depending on the reader’s objectives. The
reader can follow the charts from Part 1 to rank the relative risk of using different
machine types under various conditions, and then seek specific information about the
equipment in Part 2. Alternatively, reading through each section in Part 2 will provide
the reader with a more complete overview of the capabilities and limitations of the
various equipment types.
The handbook is intended to provide a broad overview of the capabilities and limitations of the various equipment types. After browsing the handbook, the reader will have
a basic introduction to the capabilities of the harvesting equipment commonly used in
British Columbia.
Background to Equipment Selection
Context for equipment selection
This section provides a very brief overview of the issues involved with equipment
selection. It is intended for readers who may be inexperienced with equipment selection, but who are required to specify equipment to use for a particular cutblock. It will
focus the reader’s attention on those factors that are most important for that cutblock.
However, this handbook does not intend to suggest that any particular make, model,
or type of equipment must be used on a specific site. That decision must rest with the
various planners and owners responsible for managing the area.
Why is equipment selection important?
Each cutblock has a set of management objectives that likely include aspects of safety,
profitability, forest health, water quality, and environmental concerns. If the equipment
and system chosen for a cutblock are mismatched to the site and stand conditions, then
it may be impossible to achieve any or all of these objectives. The ramifications of
improper equipment selection may range from unsafe working conditions to unacceptable costs to charges under the applicable forest-practices legislation. Making sound
choices aims to reduce the risk of those events happening.
Who selects the equipment and when?
Many people make decisions about equipment selection at different times. These
include:
• Equipment owner or corporate financial officer — matches the equipment fleet to
the long-term expected site conditions to ensure that the equipment is profitable
to operate over the long term. Decisions made when buying the equipment.
• Layout personnel — ensures that the road and cutblock boundary locations are suitable to the type of equipment that will be used for harvesting. Decisions made at
layout time.
• Planner and woodlands manager — ensures a balance between equipment availability and number of cutblocks laid out for particular equipment types. Decisions
made periodically (e.g., monthly or annually).
Background to Equipment Selection
5
• Woodlands supervisor or contractor — assigns specific machines to work on specific sites. Fine-tunes the layout and operating techniques to match the site characteristics. Decisions made at harvest time.
What factors affect equipment selection?
Terrain The factors to consider include slope, ground profile, streams and wetlands,
gullies, and roughness. These factors affect the ability of the equipment to travel over
the ground to reach the operating sites. Driving access is required to all parts of the
cutblock for ground-based equipment, while cable and aerial systems allow for remote
access. Ground-based systems may cause more soil disturbance than cable or aerial
systems, especially on steep slopes or rough ground. The ground profile is critical to the
success of cable systems — the layout must be engineered with adequate deflection and
ground clearance to support the intended payload. In general, ground-based systems
are less expensive to own and operate than cable systems, which are less expensive than
aerial. Sensitive areas must be considered carefully to ensure that soil disturbance or
other environmental damage does not occur.
Soil characteristics to consider during equipment selection include texture, moisture content, and seasonal impact. These factors affect the bearing strength of the soil,
and its ability to withstand machine traffic without degradation. Fine-textured soils and
moist soils are more sensitive to machine traffic than coarse-textured or dry soils. Frozen or deep-snow conditions allow ground-based machines to access ground that may
not support traffic during non-frozen conditions.
Soil
Timber characteristics The following timber characteristics can influence equipment
selection: tree size, volume per hectare, and timber quality. There are two primary concerns: (1) the physical ability of the equipment to handle the trees without causing unsafe working conditions or causing damage to the equipment, site, or timber; and
(2) harvesting economics for both per-tree and per-cutblock costs. Small trees are less
economical to harvest than large trees, and small cutblocks are less economical than
large cutblocks. Fixed costs such as road construction must be amortized over the volume harvested from the cutblock, and lower volumes per hectare result in smaller
cutblock volumes and higher costs. Harvesting systems with high mobilization costs,
such as cable or aerial systems, are especially susceptible to the effects of low volumes
per hectare. The timber quality affects the timber value, and thus the harvesting economics. Large trees may be too heavy for some equipment to handle, and small trees may
be damaged by large equipment.
The timber must be harvested safely and economically for the
licensee and its contractors to ensure worker safety and to remain in business. All costs,
including ownership, operating, and maintenance costs, must be considered
Business requirements
Business requirements, as opposed to site characteristics, may impose conditions on the
harvesting operations. These business requirements may include the operating season, timber flow, mill’s log specifications, amount of work available, unique operating methods,
labour availability, and equipment availability, service, and transportation.
Each company chooses harvesting equipment and methods that it feels best meets its
corporate objectives, and different corporate objectives can be reflected in the equipment selection. For example, the mill may be equipped to accept a certain wood form
as input (e.g., whole stems, logs, short logs); therefore, the harvesting system must be
6
Introduction
geared to produce that wood form. This choice can have ramifications throughout all
phases of harvesting.
Weather and climate Inclement weather such as rain or wind can affect the severity of
soil disturbance or can cause more hazardous working conditions. Saturated soils are
more susceptible than dry soils to damage from machine traffic. Wind is especially problematic for hand-fallers. Deep snow can provide a protective ground covering for
machines to travel upon, although it can also impair machines’ mobility. Snow on steep
terrain creates a safety hazard for on-the-ground workers because of slippery footing.
Silvicultural system The silvicultural system is significant for equipment selection
because some machines can maneuver better than others between the standing trees
and extract logs from a partial cut without damaging the residual stand or affecting
future growth potential. Machine size and maneuverability are important issues to consider in relation to silvicultural systems.
Legislation, regulations, or permit requirements Some of the operating parameters in the
cutblocks result from legislative requirements or permit conditions required by government. For example, utilization standards may include acceptable limits for stump heights
and levels of breakage. Soil disturbance guidelines can limit the number of roads, trails,
and other access structures that are allowed to be constructed on various sites, and thus
affect the range of candidate equipment.
Planning horizon for equipment selection
Selecting the equipment for a particular site must be made within the current corporate
and regulatory environment. Some typical questions to ask might be: What equipment
is available? What is the long- and short-term budgeted production? What are the log
quality requirements for the mill? What capital is available? What special environmental factors must be considered? Sometimes, different equipment can be selected upon
short notice, but more often the equipment available for any specific site is limited by
budgets or by other long-term commitments. Therefore, harvesting equipment selection
must be considered over both the long term and the short term.
Over the long term, the general site and timber characteristics that are expected must
be examined, and the equipment fleet selected to suit those conditions. The time horizon, which is related to budget and capital amortization, is generally three to five years
or longer for major capital purchases.
Contractual and corporate obligations mean there is less flexibility to choose different
equipment in the short term, and the equipment selection question is reversed. The site
and stand characteristics remain important, but instead of asking “What equipment is
suited to this site?” the question becomes “What site is available to use this equipment?”
The process of matching equipment to sites becomes a matter of ensuring an adequate
number of suitable sites for the available equipment.
These long- and short-term considerations apply not only to large companies, but also
to independent contractors and planners with the Ministry of Forests Small Business
Forest Enterprise Program. The difference between them is a matter of degree, especially
regarding the control over each planning level. Large companies that incorporate both
planning and operational functions control their long- and short-term planning — to a
large extent, they control their own destiny within their corporate structure. On the other
hand, long- and short-term plans are provided to contractors — their equipment selection decisions are based on the information contained in the plans provided to them.
Background to Equipment Selection
7
Planners for the Ministry of Forests Small Business Forest Enterprise Program do not
purchase equipment themselves, but they do influence the choices made by logging
contractors by way of their future timber sale opportunities and the conditions placed
on specific timber sales.
What constitutes successful harvesting operations?
The success of a particular harvesting system can be measured against operational and
environmental criteria. The operational criteria include such factors as safety, profitability,
and log quality, while the environmental criteria include water quality, soil disturbance,
and residual stand protection. These objectives will change in importance depending
on the site and the outlook of the observer. For example, the contractor may rank profitability before residual stand protection, while the forester may reverse their importance.
However, both operational and environmental criteria must be considered to harvest
timber successfully in today’s corporate and environmental climate.
8
Introduction
EQUIPMENT DESCRIPTIONS
The various types of harvesting equipment are described in two sets of graphics. The first
set summarizes the costs and characteristics of various equipment types in a tabular
format using a High-Medium-Low rating system. By scanning the “characteristics”
tables, the reader can quickly determine whether a particular type of equipment is suitable to various site conditions and operating environments.
The second set identifies the key factors that affect the likelihood of conducting successful operations with various equipment types. By following through these charts, the
reader can quickly identify those site characteristics that imply high risk with any given
type of equipment.
Neither set of graphics attempts to identify the “correct” equipment for a particular site
because there are usually too many variables for there to be just one feasible solution.
Instead, these graphics can help to focus the reader’s attention on those equipment types
that have the lowest risk and the highest probability of achieving success.
After reading this section, the reader may wish to consult Part 2 of the handbook for more
detailed information about specific equipment types.
What Equipment To Consider?
The tables and charts presented later in this section have been developed assuming that
all equipment types are available to be used on any given site, and that a selection process will eliminate the less suitable types. Given the full range of equipment to choose
from, cost is often the first selection criteria. However, cost is not the only consideration, and depending on the circumstances, may not even be the primary consideration.
For example, a cutblock with sensitive soils may require specialized equipment for
harvesting to proceed at all, and costs become a secondary consideration.
The planner must carefully consider all available options for harvesting systems, and a
starting point is to consider the range of equipment costs. Relative cost ranges of various equipment types are shown in Table 1.
Costs can be considered in various ways, including unit production costs, ownership
costs, and total costs. Unit production costs include the machine’s operating and maintenance costs coupled with an estimate of productivity. Ownership costs include the
machine’s purchase price, plus interest on capital and other fixed costs such as insurance. Total costs represent the total cost of owning, operating, and repairing the equipment over its lifespan. Low initial costs may not necessarily result in the lowest total costs
over the equipment because of high maintenance costs or low productivity.
Costs can also vary widely depending on operating conditions and techniques. For
example, Table 1 lists loader-forwarders in the low-cost category for unit production
costs, which is accurate for easy terrain with large timber, but is inaccurate for rough
terrain or small timber. The unit production costs for Table 1 are applicable under ideal
conditions.
Total costs are important to consider, but also difficult to quantify because of different
operating conditions and techniques, and widely varying maintenance regimes. Total
costs are omitted from Table 1 because of their even wider variability than unit production costs and capital costs.
What Equipment To Consider?
9
Unit production costs and ownership costs should be considered separately because they
are not always related. For example, helicopters have both high unit production costs
and high ownership costs, while clambunk skidders have high ownership costs but low
unit production costs. Furthermore, different companies place different emphasis on unit
production and ownership costs.
In the long term, all options from Table 1 should be considered, but in the short term
only those machine types that are available need be considered.
Table 1. Relative cost ranges for primary transport equipment under ideal conditions
10
Cost range
Unit production costs
Ownership costs
Low cost
Wheeled skidder
Loader-forwarder
Cherry picker/Super snorkel
Grapple yarder
Wheeled skidder
Horse
Small-scale equipment
Medium cost
Crawler skidder
Clambunk skidder
Forwarder
Horse
Small-scale equipment
Highlead
Small single-span skyline
Crawler skidder
Flex-track skidder
Highlead
Small single-span skyline
Multi-span skyline
High cost
Flex-track skidder
Large single-span skyline
Multi-span skyline
Medium-lift helicopter
Clambunk skidder
Forwarder
Cherry picker/Super snorkel
Loader-forwarder
Grapple yarder
Large single-span skyline
Medium-lift helicopter
Very high cost
Heavy-lift helicopter
Heavy-lift helicopter
Equipment Descriptions
Equipment Characteristics Summarized by Phase
After using ownership costs or unit production costs to rank the various types of available equipment, the next step is to use equipment characteristics to match equipment
to operating conditions. To help with this process, this section presents tables for each
harvesting phase that summarize the major features of different equipment types. Four
tables are presented: primary transport in Table 2, falling in Table 3, processing in
Table 4, and loading in Table 5.
The rows in each table list the important characteristics that can be used to match equipment to operating conditions. The various types of equipment that can be used for each
phase are listed in columns across the tables, and the entries in the tables contain a
variety of information. In some cases, a High-Medium-Low system is used to rank the
various equipment according to each characteristic. In other cases, the tables list actual
values such as maximum yarding or skidding distances or maximum slope limits for
ground-based equipment. Lastly, “+” or “-” symbols are used to indicate whether a
particular feature will enhance or detract from the various characteristics.
In keeping with the objectives of this handbook, the terms “high, medium, and low” are
left undefined in the tables. Defining these terms would tend towards a “cookbook”
approach for determining the single “correct” answer, which the handbook tries to avoid.
Instead, the tables should be used only to rank equipment types relative to one another.
For example, the required operator skill level for skidders is listed as low, implying only
that less skill is required to operate skidders than clambunks, forwarders, or other machines. This list does not say that skidder operators are unskilled. On the contrary, skidder
operators require a significant amount of skill and training, especially considering the
consequences if the machines are operated in an unsafe or environmentally risky fashion. However, the mechanical simplicity of skidders as compared with forwarders and
the reduced manual dexterity as compared with yarding cranes places skidders in the
“low” operator skill category.
Using the list of equipment ranked by cost, the reader should determine whether each
type of equipment remains a candidate for consideration. As stated previously, costs may
not be the primary consideration, and the list of candidate equipment could be ranked
by different criteria. Items such as skidding distance, tree size, slope, and susceptibility
to high soil moisture will help to eliminate types that are unsuitable for the anticipated
site conditions. Other items such as safety hazards, daily productivity, ability to work
independently, and capital investment will help to determine whether the equipment
will fit within the corporate organizational structure.
After completing the rankings from these tables, the reader should move on to the next
section — determining various risk levels.
Risk-level Assessment
Risk levels
Acceptable results by a specific equipment type cannot be guaranteed on a given site
because too many variables are involved — prescription, operator skill and attitude,
weather, business objectives, and quality of site description. Instead, an element of
uncertainty or risk is implied, especially when operating techniques are considered. For
example, wheeled skidders can be operated safely on gentle slopes, but become
unstable on steep slopes especially if turning is required. To increase the safety factor,
skidders can be operated straight down the slope or from excavated trails. However,
Risk-level Assessment
11
Table 2. Characteristics of primary transport equipment
12
Equipment Descriptions
Table 3. Characteristics of falling equipment
Risk-level Assessment
13
Table 4. Characteristics of processing equipment
14
Equipment Descriptions
Table 5. Characteristics of loading equipment
Risk Level Assessment
15
excavated trails may have an impact on soil erosion, water quality, or the amount of site
disturbance. Similarly, flotation mats can allow excavators to work on soft ground, but
may slow machine travel and reduce productivity.
Most importantly, each machine type is suitable to a range of conditions as defined by
its basic features. When operating the machine within its appropriate range, the risk of
exceeding operational and environmental limits is minimized, but operating outside the
range will increase the risk of generating unacceptable results. Even the most
benign harvesting system can produce unacceptable results if used inappropriately, and
seemingly unsuitable equipment can be made suitable by incorporating appropriate
techniques.
Under this concept, selecting the appropriate equipment for each site becomes a matter of matching features to risk. The planner must understand the basic features of the
equipment, the range of operating techniques, the influence of site conditions and the
external requirements that might be imposed, and how these four factors are related to
one another by risk levels. Combinations of equipment and conditions with low risk
levels should be considered rather than those with higher risk levels. The use of higher
risk combinations may be appropriate under certain operating conditions or to achieve
specific goals, but such a selection should be made only with a full understanding of
all the potential risks and benefits.
This handbook uses a system of risk evaluation, and Table 6 defines various risk levels
on a scale from 1 to 6. These risk levels are not absolute; instead they indicate the relative amount of risk of operating the machine under varying site and objective conditions.
A low risk level indicates a good chance of successful operations, while a high number
indicates a high risk of failure.
Some high risk activities are constrained by environmental considerations (e.g., high
likelihood of soil degradation by wheeled skidders on moist, fine-textured soils), while
others are constrained by operational considerations such as productivity (e.g., poor
performance of large highlead systems with small trees). In either case, the risk level is
shown as a single value, and the underlying cause is not indicated in the charts. The
descriptions in Part 2 of the handbook will provide additional detail and explanation
regarding the cause of the high risk level.
The high-risk levels as defined in Table 6 and used in the charts that follow are quite
definite, whereas the lower levels should be considered more as general guidelines. For
Table 6. R isk-level d escrip tions
R isk Level
16
Equipment Descriptions
D escription
1
M inim al risk, best operating con ditio ns.
2
G enerally accep table; n orm al operatin g co nditions. U nusual
circum stan ces m ay increase risk.
3
A cceptable under m any condition s, bu t exercise cautio n.
4
R isky; good reaso ns or special operating techniques required to
op erate un der these cond itio ns.
5
H ighly risky; exceptio nal circum stances required to operate
un der these condition s. Special p lanning and operating
techn iques w ill be required.
6
N ot recom m end ed.
example, Chart 13 for multi-span skylines lists only four possible outcomes, three of
which are risk level 5 or 6, and one of which is risk level 1. This should be interpreted
as saying “Three factors rule out multi-span systems. In the absence of these factors, the
system is feasible.” In contrast, Chart 15 for large skylines lists more factors, some of
which have mid-level risks. These mid-level risks indicate that the equipment and site
are compatible, but caution should be exercised.
Risk factors that apply to all harvesting systems are shown in Table 7. These factors should
be considered, and used to modify the risk factors shown in the individual charts.
Key factors
The following charts list the key factors to consider when determining the suitability of
each machine type for operating on a particular site. Only the most important factors
have been listed — clearly, other factors must be considered when choosing equipment,
and the reader should refer to Part 2 of the handbook for additional information. This is
especially critical for the low- and mid-level risks — whereas the high-level risks are
more definite.
The charts are presented as flowcharts starting from the upper-left corner of each chart.
The various factors are shown in diamond-shaped boxes, and the risk levels are shown
in small rectangular boxes. Choose one of the paths leading from each decision box as
determined by the site conditions. The most critical factors are listed first, and may constitute a simple go/no-go decision. For example, using wheeled skidders on fine-textured
soils with high moisture content is not recommended. The factors further down in the
chart typically have more feasible outcomes — follow the path that most closely
Table 7. Risk factors applicable to all harvesting equipment
Factor
Comment
Operator experience,
attitude, and history
Risk is decreased with an experienced operator who has worked
successfully under similar conditions in the past, and has
demonstrated a desire to do a proper job.
Contractor experience,
attitude, and history
Risk is decreased with an experienced contractor who has
worked successfully under similar conditions in the past, and
has demonstrated a desire to do a proper job. Effective
communications between the planners and the workers and
adequate supervision decrease the risk of a mishap caused by
misunderstood instructions.
Weather
Inclement weather, especially excessive rainfall, increases the risk.
The risk of causing soil disturbance increases with higher soil
moisture content. Maintaining a flexible schedule, with the ability to
work on different areas as required by weather conditions, reduces
the risk.
Sensitive zones
Working in the vicinity of riparian zones, or other sensitive zones,
increases the risk. Operators should always take extra care when
working in sensitive zones.
Tree size
Risk is minimized when the tree size is matched to machine size.
Trees that are too small decrease productivity and increase costs,
while trees that are too large can overwork the machine, causing
mechanical failure or environmental damage.
Timber quality
Risk is increased with poor-quality timber because of reduced
values. Poor-quality timber requires as much, or more, time for
processing, yet returns a smaller profit.
Risk-level Assessment
17
describes the site characteristic. Proceed through the chart until you arrive at a risk-level
box.
In some cases, a first-mentioned factor on the chart may result in a high, but non-limiting, risk level (e.g., in Chart 15, non-clearcuts are ranked as risk level 4). On the same
chart, another factor may be ranked with a higher risk level (e.g., poor deflection is
ranked as risk level 6). This result should not be interpreted as saying that poor deflection in a non-clearcut will result in risk level 4. Obviously, the higher risk level will
prevail.
Comments at the bottom of each chart list additional factors that apply for all types of
sites, and should be considered in assessing the risk level. Table 7 lists risk factors that
should be considered for all types of equipment. Finally, the contractor and operator may
employ special operating techniques that can modify the risk levels.
18
Equipment Descriptions
Key Factors for Primary Transport Equipment
Chart 1. Wheeled skidders.
• The ability to turn skidders safely is reduced on steep slopes. The presence of large obstacles such as boulders,
depressions, or windfalls will increase the risk, especially on steep slopes, because they increase the difficulty of
turning around the machine. Benches may increase the opportunity for turning safely. Obstacles also reduce the
travel speed and increase the travel distance.
• Grapple skidders are best suited for use with mechanical falling and bunching equipment, which requires that the
tree size be within the operating range of the falling equipment. Grapple skidders enable roadside operations, which
can reduce production costs. Swing-boom grapples reduce the risk on steep ground. On wetter sites, line skidders
can drop their load and move forward to more firm terrain before winching the load, thus reducing the risk of soil
disturbance.
Key Factors for Primary Transport Equipment
19
Chart 2. Crawler skidders.
• The ability to turn skidders safely is reduced on steep slopes. The presence of large obstacles such as boulders,
depressions, or windfalls will increase the risk, especially on steep slopes, because they increase the difficulty of
turning around the machine. Benches may increase the opportunity for turning safely. Obstacles also reduce the
travel speed and increase the travel distance.
• Grapple skidders are best suited for use with mechanical falling and bunching equipment, which requires that the
tree size be within the operating range of the falling equipment. Grapple skidders enable roadside operations, which
can reduce production costs. Swing-boom grapples reduce the risk on steep ground. On wetter sites, line skidders
can drop their load and move forward to more firm terrain, thus reducing the risk of soil disturbance.
• Low travel speed makes crawler skidders more suited to short skidding distances.
20
Equipment Descriptions
Chart 3. Flex-track skidders.
• The ability to turn skidders safely is reduced on steep slopes. The presence of large obstacles such as boulders,
depressions, or windfalls will increase the risk, especially on steep slopes, because they increase the difficulty of
turning around the machine. Benches may increase the opportunity for turning safely. Obstacles also reduce the
travel speed and increase the travel distance.
• Grapple skidders are best suited for use with mechanical falling and bunching equipment, which requires that the
tree size be within the operating range of the falling equipment. Grapple skidders enable roadside operations, which
can reduce production costs. Swing-boom grapples reduce the risk on steep ground. On wetter sites, line skidders
can drop their load and move forward to more firm terrain, thus reducing the risk of soil disturbance.
• The tracks for flex-track machines conform more closely to the ground profile than for conventional tracked skidders.
This feature distributes their weight more evenly, allowing them to operate on soft ground and up adverse slopes
with less soil disturbance.
Key Factors for Primary Transport Equipment
21
Chart 4. Clambunk skidders.
• The presence of large obstacles such as boulders, depressions, or windfalls will increase the risk because they
reduce the travel speed and increase the travel distance.
• The risk level increases for low volumes per trail (i.e., for “shallow” or low volume per hectare cutblocks). The
clambunk will be unable to obtain a full load, making it uneconomic to operate unless the skidding pattern is altered
to attain full loading.
• Clambunks are best suited for use with mechanical falling and bunching, which requires that the tree size be within
the operating range of the falling equipment.
22
Equipment Descriptions
Chart 5. Forwarders.
• The risk level is very high if the mill and truck fleet are unable to accept cut-to-length logs, although these limitations are imposed by business requirements, not by the site characteristics. Timber sales to other companies and
other options for transporting the logs should be considered.
• Large obstacles such as boulders, depressions, or windfalls will increase the risk because they reduce the travel
speed and increase the travel distance.
• The tree size must be suitable for the feller-processor that works with the forwarder. Large trees may require falling and processing with additional equipment.
• Depending on machine size, the high degree of maneuverability between standing trees makes forwarders well
suited to partial cutting operations.
Key Factors for Primary Transport Equipment
23
Chart 6. Loader-forwarders.
• Distance for each “tier” or “chuck” will vary depending on the size of the machine, the length of the timber, and
the decision to buck trees into log lengths.
• The risk level increases for wet or fine soils and for small trees.
24
Equipment Descriptions
Chart 7. Cherry pickers and super snorkels.
Chart 8. Horse.
• Skidding with horses is enhanced on a snowpack because of reduced friction. Risk increases for slopes over 15%
under frozen conditions because of the potential for logs to slide downhill and strike the horse.
• The trails where the horses walk must be cleared of debris before skidding.
Key Factors for Primary Transport Equipment
25
Chart 9. Small-scale equipment.
• Many types of small-scale equipment are available with a wide range of capabilities and key factors. They are used
in niche applications, typically where tree size is small and productivity is low. Beyond that, examine the specific
type of equipment proposed to determine whether it is usable.
26
Equipment Descriptions
Chart 10. Highlead yarders.
• Highlead yarders can continue to work even if the butt-rigging drags on the ground, although this practice may
result in excessive soil disturbance and low productivity.
• Landing chance refers to the ability to build and use suitable landings. Poor landing chance may be caused by difficult terrain or by the combination of terrain, deflection, and the tower location within the landing.
• Tree size and volume per hectare must be evaluated in relation to the specific machine, with a minimum economic
volume ranging from 150 to 350 m3/ha depending on machine size.
• Anchors may consist of large tree stumps, several smaller trees or stumps, or fabricated anchors such as a buried
log or rock bolts.
• Cable extensions can be used to reach logs beyond the yarder’s normal working distance.
Key Factors for Primary Transport Equipment
27
Chart 11. Swing yarders – grapple.
• The risk level is increased where mobile backspars cannot be used — conventional anchors must be available
in their place. Anchors may consist of large tree stumps, several smaller trees or stumps, or fabricated anchors
such as a buried log or rock bolts.
• The risk level increases for small tree size because the trees are picked up individually. Mechanical falling and
bunching can reduce the risk.
28
Equipment Descriptions
Chart 12. Swing yarders – slackpulling carriage and chokers.
• Anchors may consist of large tree stumps, several smaller trees or stumps, or fabricated anchors such as a buried
log or rock bolts.
Key Factors for Primary Transport Equipment
29
Chart 13. Multi-span skylines.
• Landing chance refers to the ability to build and use suitable landings for extraction and subsequent phases. Poor
landing chance may be caused by difficult terrain or by the combination of terrain, deflection, and the tower
location within the landing.
• Risk level increases as the volume per hectare decreases.
• Although intermediate supports allow for yarding in areas of poor deflection, risk increases as the number of intermediate supports increases.
• Payloads can be lifted over intervening obstacles depending on the ground profile, the layout, and the equipment
capability.
• Anchors may consist of large tree stumps, several smaller trees or stumps, or fabricated anchors such as a buried
log or rock bolts.
• Cable extensions can be used to reach logs beyond the yarder’s normal working distance.
30
Equipment Descriptions
Chart 14. Small, single-span skylines.
• Landing chance refers to the ability to build and use suitable landings for extraction and subsequent phases. Poor
landing chance may be caused by difficult terrain or by the combination of terrain, deflection, and the tower
location within the landing.
• Risk level increases as the volume per hectare decreases.
• Payloads can be lifted over intervening obstacles, depending on deflection and clearance.
• Anchors may consist of large tree stumps, several smaller trees or stumps, or fabricated anchors such as a buried
log or rock bolts.
• Cable extensions can be used to reach logs beyond the yarder’s normal working distance.
Key Factors for Primary Transport Equipment
31
*
Chart 15. Large, single-span skylines.
• The term “large” refers both to the yarder size and the skyline span — large tower-mounted yarders and European
cable cranes both qualify as “large.” However, the European cable cranes are better able to operate in non-clearcut
silvicultural systems, and their risk would be lower than shown in the chart.
• Landing chance refers to the ability to build and use suitable landings for extraction and subsequent phases. Poor
landing chance may be caused by difficult terrain or by the combination of terrain, deflection, and the tower
location within the landing.
• Payloads can be lifted over intervening obstacles depending on deflection and clearance.
• Risk increases with too-large deflection because of the increased time required for the chokers to travel between
the carriage and the ground.
• Anchors may consist of large trees or stumps, or fabricated anchors such as a buried log or rock bolts.
• Cable extensions can be used to reach logs beyond the yarder’s normal working distance.
32
Equipment Descriptions
Chart 16. Helicopters.
• Suitable landings are large enough to handle the expected volume of logs without causing delays. Flying, processing,
storage, and loading must all be accommodated. A separate landing for helicopter fueling and maintenance is
required.
• Risk level increases when multiple hookup sites are not available, with long flying distances, and with adverse or
very steep favourable slope between the hookup site and the landing.
• Poor weather such as high wind or reduced visibility can affect the ability of the helicopter to fly safely.
• Payloads can be lifted over intervening obstacles.
Key Factors for Primary Transport Equipment
33
Key Factors for Falling Equipment
Chart 17. Hand-fallers.
• Hand-fallers can work on almost any site, within the limits of economics and safety.
• Falling small trees by hand is expensive, especially after considering the costs for extraction. Except with very small
trees, hand-fallers are unable to build bunches.
• Hand-falling in decadent timber and bucking timber on steep, broken terrain are especially hazardous.
34
Equipment Descriptions
Chart 18. Feller-bunchers and feller-directors.
• Maximum tree size depends on the make and model of the carrier and head. Typical maximum tree diameter is
about 60 cm, although larger heads up to 75 cm are available. Larger trees can be cut by approaching the tree
from two or more sides.
• Feller-directors can handle larger trees than feller-bunchers, but they are poorly suited to making bunches.
Key Factors for Falling Equipment
35
Chart 19. Feller-processors.
• This chart applies to feller-processors mounted on articulated, rubber-tired carriers. Use the “feller-buncher” chart
for single-grip feller-processors mounted on excavator-style carriers.
• The maximum tree diameter for current single-grip feller-processors is about 50 cm. Current double-grip fellerprocessors can handle trees to about 65 cm diameter.
• Feller-processors must be able to accurately and reliably measure log lengths.
36
Equipment Descriptions
Key Factors for Processing Equipment
Chart 20. Hand-buckers.
• Hand-bucking can be used on almost any site, within the constraints of safety and economics. Since hand-buckers
require support equipment to move the logs, the bucker and support equipment must be able to work together
safely. This requires adequate time between cycles of the loading or skidding equipment, and adequate space to
spread out the logs for the bucker to examine and cut each log. Such conditions may be impossible to achieve on
sites with a high proportion of small trees.
Key Factors for Processing Equipment
37
Chart 21. Dangle-head processors.
• Dangle-head processors are typically used for smaller trees, with a maximum diameter of about 50 cm; however,
some models can process logs up to 80 cm diameter. Trees larger than the rated maximum diameter can be handled by grasping the tree above the butt, where the diameter is smaller. Trees can also be left lying on the ground,
and the processing head passed over them without actually lifting the tree.
Chart 22. Stroke delimbers.
• The maximum tree size for stroke delimbers is governed by the diameter of the tunnel through the machine — the
trees must be able to fit through the tunnel.
• Stroke delimbers are less efficient for small trees than dangle-head processors because they pass over each log twice
to complete the processing cycle. However, stroke delimbers can process several small trees simultaneously.
38
Equipment Descriptions
Key Factors for Loading Equipment
Chart 23. Front-end loaders.
• Wheeled front-end loaders can be moved quickly between sites several kilometres apart. Loaders on tracked carriers require low-bed transportation.
Key Factors for Loading Equipment
39
Chart 24. Hydraulic loaders.
Chart 25. Butt ’n top loaders.
• Suitability of a cutblock for roadside logging is often determined by the ability of the butt ’n top loader to operate
adjacent to the road. Sideslopes must be low enough for the loader to operate safely.
40
Equipment Descriptions
Chart 26. Line loaders.
• Line loaders can be moved relatively easily between loading sites up to several hundred metres apart, and are
often used to service two towers simultaneously. Landings further apart pose difficulty for simultaneous operation
because of low travel speeds, especially for track-mounted loaders. Low-bed transportation over longer distances
is required. Rubber-mounted loaders can travel farther under their own power, but travel remains slow.
Key Factors for Loading Equipment
41
EXAMPLES
These examples demonstrate how information can be obtained from the handbook to
help match equipment to the site. The examples have been based on hypothetical scenarios that could be encountered by industrial or agency planners.
These examples illustrate that the handbook’s purpose is to identify issues and concerns,
and to evaluate the risks associated with combinations of site conditions and equipment.
The handbook is not meant to provide the single “correct” answer about what equipment is suited to any particular site.
Example 1: Change Harvest Season
A cutblock has been planned and approved for winter harvesting, but corporate log-flow
requirements have made it important to advance the harvesting schedule, perhaps to late
summer or early fall. What are the important issues that must be addressed with harvesting the cutblock earlier in the season? Will the same equipment be suitable? If not,
what different equipment or operating techniques will achieve acceptable results?
The cutblock is proposed for clearcut harvesting, using typical roadside equipment
comprising a feller-buncher, grapple skidders, stroke delimbers, and butt ’n top loader.
The timber is small-diameter pine on rolling terrain, and the roads were laid out for a
maximum of 250 m skidding. The maximum sideslope is about 30% and the soils are
fine-textured. The proposed plan specifies harvesting under dry or frozen conditions.
Scan the column labelled “wheeled skidder - grapple” in Table 2 to determine what
impacts could result from the proposed change to the harvesting schedule. Wheeled
skidders require high soil strength, and have low to moderate ability to avoid ground
disturbance, especially when the soil moisture content is high.
Figure 1
Rubber-tired skidders
may be a high-risk
option for non-frozen
conditions unless
weather conditions
are favourable.
Chart 1 confirms this —
operating on fine-textured
soils under wet conditions is
rated at risk level 6 (Table 6).
Clearly, soil disturbance will
be a significant concern.
The requirements and limitations of the skidding
equipment will not be
changed under a different
harvesting schedule, so the
planner must evaluate the
risk of operating under nonfrozen conditions. What is the likelihood of experiencing a period of sustained dry
weather when the skidders may be able to operate successfully? If the likelihood of dry
weather is low, resulting in a high risk of soil disturbance, then changes to the operating techniques or equipment will be required. Information listed in the Index under “soil
disturbance - compaction - skidder” and “soil disturbance - rutting” describe wide tires
and devices to fit over the skidder tires to reduce their ground pressure. These devices
could reduce the risk of causing soil disturbance.
However, the rubber-tired skidder remains a high-risk option even with tracks or wide
tires, so alternative equipment should be considered. Clambunks, forwarders, loader-
42
Examples
forwarders, small-scale equipment, and horse logging are the ground-based options with
greater ability to avoid ground disturbance (Table 2). The latter two options are high risk
for this scenario because of their low productivity. Although the forwarder is less
susceptible to high soil moisture, it could be high risk because it requires specialized
trucks and mill configuration (Chart 5) that may not be available. Specialized falling and
loading equipment will also be required. Clambunks (Index: clambunk) may be better
suited to the soil conditions than the skidders. Loader-forwarding could be an option,
but the small timber size and long skidding distances increase the risk. Flex-track skidders
are also rated in Table 2 with a low–moderate ability to avoid ground disturbance, but
their risk on moist, fine-textured soils is rated slightly lower than skidders (Chart 3). They
may be worth considering.
Cable equipment may provide an alternative more suited to reducing soil disturbance,
but higher operating costs will increase the risk. Furthermore, the yarder must be suitable for roadside operations to fit with the processing and loading equipment,
eliminating highlead yarders from consideration. The small tree size eliminates large
equipment, although bunching could help to reduce the risk. Adequate deflection and
clearance will be critical to avoid soil disturbance (Chart 14). Rolling terrain with maximum 30% sideslopes over yarding distances of 250 m will make it difficult to achieve
adequate clearance with a short yarder. Multi-span skylines could be considered.
The only alternatives to the wheeled skidder that seem viable are the clambunk skidder
and the flex-track skidder. The forwarder may be viable if the corporate infrastructure
supports shortwood logging.
Clearly, any equipment changes required in this scenario will be short term, and therefore must be confined to equipment that is readily available for hire. Most of the alternative equipment is capital-intensive (Table 1), and is likely to be gainfully employed
and unavailable for a short-term rental. Furthermore, all the alternatives are more
expensive than the original proposal — the planner must evaluate the benefit of the
altered harvesting schedule with the added costs.
Example 2: Review Development Plan
As a Small Business forester for the British Columbia Ministry of Forests, you are responsible for preparing forest development plans for the Small Business Forest Enterprise
Program. An area of your development plan includes a coastal cutblock where the layout contractor has proposed skyline yarding over a creek. You are unfamiliar with
skyline systems, and want to ensure that the proposed harvesting will achieve all the
operational and environmental objectives. What are the issues that should be addressed
in your review? What alternatives should be considered?
The cutblock is located in an incised valley with sideslopes averaging about 70%, although the sideslope reaches about 100% at the higher elevations. A road was constructed about 15 years ago to harvest the timber on one side of the creek using a grapple
yarder. The cutblock was reforested after harvesting, and now supports a stand of trees
about 5–7 m tall. The timber on the far side of the valley was not harvested
because of difficult terrain. It has numerous rock bluffs dispersed throughout the standing
timber, which would result in extremely expensive road construction. A narrow band
of trees left adjacent to the creek after the original harvesting has not sustained any significant amount of windthrow. A similar buffer strip is proposed for the far side of the
creek. Two landings are proposed on the existing road for skyline yarding, and the maximum distance from the landings to the cutblock boundary is about 700 m.
Example 2: Review Development Plan
43
Figure 2
Large skyline towers
can suspend logs over
streams providing the
conditions are suitable
Table 2 indicates that the proposed large, single-span skyline will adequately address any
concerns about soil disturbance, but the crossstream yarding concerns you with the possibility of introducing debris into the stream. Will
the skyline be able to lift the logs clear of the
buffer strip? Chart 15 indicates that deflection
is a primary consideration for large skylines,
and the Index points to several areas with information about deflection. Clearly, both deflection and clearance are important, so you make
a note to ask the layout contractor for representative deflection lines. You will ask about the
amount of deflection, and the amount of clearance below the carriage. You also note to ask
whether the trees will be yarded full-length, or
will they be bucked beforehand? This will affect
the required amount of clearance over the
standing trees. You learned from the information
under “hand-falling” and “hand-bucking” that
on-site bucking is difficult and dangerous in such steep terrain. If clearance is inadequate,
you will ask what plans have been made for corridors through the standing timber.
You also notice from Chart 15 that the landing chance and anchors are critical for successful skyline operations, so you will ask about the landings (Index: landing - yarding).
The original harvesting was done by grapple yarders, which do not require landings, but
the skyline yarders will need landings. Will the landings encroach on the plantation, and
will they have adequate space to accommodate the yarding debris? What anchors are
available at the landing to hold the tower (Index: anchor - guyline), and what anchors
will be required at the tailholds? Will the anchors be located at the cutblock boundary,
or will they be extended above the cutblock boundary to increase deflection
(Index: anchor – backspar)?
You make another note to ask the layout contractor whether alternatives to cross-stream
yarding have been considered. Clearly, ground-based systems are impractical because
of the steep and difficult terrain (Table 2), but you want to ensure that all the options
have been considered. Alternative yarding systems would involve building a road on the
other side of the creek, so you make a note to ask whether a road survey was conducted
on the far side, and if so, why it was not chosen for construction. You know from Chart
10 that highlead systems are more tolerant of poor landings than large skylines, so you
will ask about potential landings on the alternative road location. You also know from
the Index information on “yarding - slope - downhill” that safety in the landing is a major
concern.
You also consider helicopter logging. You know from Table 1 and Table 2 that helicopter extraction is more expensive than skylines, but you want to ensure that all alternatives have been explored. You know from the descriptions of helicopters (Index:
helicopter) that the helicopter must be matched in size to the timber resource and that
bucking the trees by weight rather than by length is important. Bucking on the steep,
broken ground may be difficult. Also, landing size and safety in the landing are major
concerns — you note to ask whether helicopter logging was considered, and if so, what
landing location would be used.
44
Examples
Armed with your new knowledge about skylines, you feel more confident that you can
ask pertinent questions about the proposed system, and any alternatives that were
considered.
Example 3: Encounter New Operating Conditions
XYZ Forest Products had been operating in consistent timber and terrain types for more
than 10 years, but is now faced with new conditions as it moves into a different area.
Previously, the average cutblock had been laid out for clearcut logging with roadside
processing, but the planners for XYZ realize this system is unsuitable for the new operating area. The slopes are steeper, and visual-quality objectives make large clearcuts
unacceptable. Partial cutting will be required. The timber size is about the same, although
the soils are generally of finer texture.
XYZ has four contractors, each producing about 120 000 m3/yr in roadside operations
for a total of 480 000 m3/yr. The total cut for the operating division will be reduced to
about 450 000 m3/yr, with the new area comprising about 50 000 m3/yr. One option
among several being considered is to retain three contractors at their current levels, and
to reduce one of the contractors to 90 000 m3/yr, working in a combination of the new
and existing operating areas.
The company, and its contractors, must determine whether the equipment that was used
previously will be acceptable for the new operating area.
Three of the contractors have very similar equipment: two feller-bunchers, two grapple
skidders, two stroke delimbers, and one butt ’n top loader. Each of the contractors has
at least one levelling-cab feller-buncher, and all of the feller-bunchers are equipped with
high-speed disc saws. The fourth contractor has different equipment: two feller-bunchers,
but neither have levelling cabs, one grapple skidder that is used as required, one
clambunk skidder, two dangle-head processors, and a butt ’n top loader.
What is the best equipment allocation for the new area?
The new operating conditions have five critical differences: steeper terrain, finer-textured
soils, partial cutting, less operating volume, and the requirement for flexibility between
the new and old operating conditions. Taking these in order, Table 2 indicates that
wheeled skidders are best
suited to slopes less than
35%. Depending on the
amount of area over 35% or
over 50%, the wheeled
skidders may be marginally
suited or completely unsuited to the new conditions
(Chart 1). Furthermore, the
requirement for partial cutting makes grapple-based
equipment poorly suited because of its limited reach
(Index: skidder - grapple).
Will the clambunk skidder be any better suited? Table 2 indicates that clambunks can
work on steeper terrain and require less soil strength, but there are three major factors
that make clambunks poorly suited to this situation: they are grapple-based, they are
Figure 3
Clambunk skidders
may be able to work
on the steeper slopes
of the new operating
area.
Example 3: Encounter New Operating Conditions
45
large, and difficult to maneuver within a partial cut (Index: clambunk - partial cutting),
and they require a large operating volume to make them cost-effective (Index: clambunk).
It appears that the present equipment fleet is not well suited to the new conditions. What
features should the company and contractor be looking for in replacement equipment?
The steep terrain, fine-textured soils, partial cutting, and low operating volume will all
be critical factors in the specification. Wheeled-based equipment may be unsuited,
depending on the steepness of the terrain, even if operations could be confined to
frozen or deep snowpack conditions to address the soil disturbance concerns. Trackbased equipment would have better stability for improved safety. For grapple-equipped
machines to work effectively, especially in partial cutting, they must be matched with
suitable felling equipment (Index: skidder - grapple), which means that a zero-clearance
feller-buncher with a levelling cab will likely be required (Index: feller-buncher –
partial cutting). Without the appropriate falling equipment, line skidders will be required
(Table 2).
Forwarders may be an option, depending on the terrain steepness, but the mill and trucking fleet must be configured to accept the different log specifications. Different felling
equipment would also be required to manufacture the short logs.
Cable equipment should also be considered, but only carriage-based yarders because
of the partial cutting (Table 2). With the projected volume (50 000 m3/yr), and typical
daily production rates, year-round operations will be required. Costs may be prohibitive with the small trees unless feller-bunchers can be used. As before, a levelling cab
will be required, but the soils must be examined carefully to ascertain if a feller-buncher
can be used during the summer. Depending on the typical ground profiles and deflection, multi-span capabilities may be necessary (Chart 13, Chart 14, Index: deflection).
Processing and loading equipment must also be considered. The traditional operating
area used roadside processing, but the new area will likely use landings because of the
steeper terrain. The butt ’n top loaders will not be suited, although the processors can
be used in roadside or landing configurations.
Lastly, the company and contractor must consider the overall effect of annual production levels. Under the scenario as presented, one contractor would be downsized to
90 000 m3 – 50 000 m3 from the new area and 40 000 m3 from the traditional operating areas. The previous equipment fleet was based on high-volume roadside logging,
and will no longer be cost-effective. What equipment will be used on that area? The
overall scenario seems unworkable, and should be reconsidered. The new operating area
requires different types of equipment, but changes cannot be made without considering the impacts on the traditional operating areas.
As stated before, the purpose of this handbook is not to identify the single “correct”
answer, but to identify issues that must be considered and how the characteristics of the
various types of equipment address those issues. The preceding examples illustrate how
to use the information in the handbook to improve equipment selection.
46
Examples